NEW YORK (Reuters) - Just weeks before the 10th anniversary of the air attacks on the World Trade Center, New York firefighters gave politicians and journalists a glimpse into what it is like to battle blazes in the skyscraper city.

It involves crawling around in the smoke and dark on a wet cement floor, drenched in sweat and clad in a bunker suit, mask and helmet and with an oxygen tank strapped to your back.

The smoke in the drills is white, or "Hollywood" smoke, nothing like the black, chemically-laced cloud of a real fire.

"If you don't have your wits about you, you can see how easy it is to get lost. Most of our training is about developing a kinetic sense of where you are," said Lieutenant Mike Cacciola, director of physical training.

The scenarios are varied and sometimes deadly and brutal.

On a bombed-out bus, there are dummies of adults and children, bleeding or without limbs. Captain Paul Nugent explained that setting priorities for victims is vital.

"Tilt his head. If he takes a breath, we take him out," he explained.

Victims of bio- or chemical attacks are referred to as "sludgems," according to Lieutenant Anna Schermerhorn-Collins, adding that firefighters are trained to spot the symptoms -- salivation, tears, urination, defecation, gastrointestinal upset, vomiting and constriction of the pupil of the eye.

Like the firefighters, police, emergency medical technicians and ironworkers who responded to the World Trade Center attacks, the instructors rely on humor to offset the horror and help them deal with their emotions.

"We want the victim kind of like a taco; we don't want the lettuce falling out," said Nugent, explaining how to strap the dummy and secure his limbs to a yellow plastic sheet, called a sked, which then is strapped to a stiff red board.

Infrared cameras help firefighters find victims, but the cameras can hide flames, and it is dangerous to dawdle.

"You pan the room to get an idea of where things are, and move, then you move again," said an instructor.

HEAVY AND HOT

Firefighting gear weighs up to 100 pounds (45 kg), not including hoses or 30-pound (13.6 kg) saws that might have to be carried up 10 floors in a building. Above that height, firefighters swing down from the roof.

"A lot of time firefighters will put the gear on and step climb on StairMaster," said Cacciola.

And the temperature is hot, very hot.

In the hallway, one team member's head gear reads 99 degrees Fahrenheit (37.2 Celsius) on the infrared camera. It's around 400 degrees Fahrenheit (204 Celsius) at the ceiling when the practice, computer-controlled fire is lit.

Putting out a fire requires getting close to the flames. Firefighters kneel in the doorway, tuck the hose under their arm and spray the water in a clockwise direction, according to Schermerhorn-Collins.

They start at the ceiling, then the floor and repeat the action again and again. The smoke must be vented between exercises, creating a haze during the descent to the hot asphalt lot and clear blue sky.

The firefighters also demonstrated the year-old, seven-pound (3.1 kg) system used to rappel down city buildings. It was designed to ensure trapped firefighters never again have to jump to their deaths.

But in New York, a city of skyscrapers, there is only enough line for 50 feet.

On September 11, 2001, 343 firefighters lost their lives.

"When you put people in a burning building, it's a fact that some people will get killed. It is a fact. It's part of our vocation," said Cacciola.